Knee joint of artificial legs



Nov. 20, 1951 J. FISCHER ETAL KNEE JOINT OF ARTIFICIAL LEGS Filed y 31, 1950 is m I n ventor: auR res/v FISCHER 1 411 R. kLasE 3 61M,

4 rraRn/EM Patented Nov. 20, 1951 OFFICE KNEE JOINT. F ARTIFICIAL LEGS J iirgen Fischer and Paul Richard Kluge, Hamburg, Germany Application May 31, 1950, Serial No. 165,154 In Germany October 1, 1948 4 Claims. 1

This invention relates to artificial legs.

One object of the invention is to provide an improved knee-joint for an artificial leg.

A further object is to provide a leg having a knee-joint such that when the leg is carrying a load the upper part of the leg is frictionally locked to the lower part of the leg.

With the above objects and further objects which appear from the following description, the invention provides an artificial leg having a simple practical knee-joint comprising a socket mounted in the upper limb and carrying pivoting means for the lower limb and vertically movable in such a way that the upper limb moves downwards when the artificial leg is loaded while on the upper and lower limbs are surfaces which correspond one to another, lie opposite one another and are inclined in relation to one another in such a manner that when the artificial leg is loaded a brake effect is produced. between the said surfaces.

In an artificial leg equipped with the kneejoint according to the invention, special knee fixing devices, such as have been provided inter alia for agricultural workers and patients who have lost both legs, and also special knee extensors, belts, and the like are not required. Moreover, the additional production of a stop for determined positions in bending and stretching is also eliminated. The stretching and bending of the knee-joint takes place during the movement of walking without any special action by the wearer. The over-stretching of the kneejoint and also lateral play are out of the question. When the upper limb is raised, 1. e., when the load is taken from the artificial leg, the brake effect can be removed simply and the knee-joint be made free once again. This ensures safe, easy, and smooth Walking with small steps.

Because of the increased safety, the user is relieved of the feeling of fear which may otherwise easily occur; this applies particularly to those subjects who have lost both legs and those whose second leg is not capable of full service, as well as in the case of subjects with poor le stumps and users of advanced age.

Finally, the invention, in consequence of its simplicity, ensures not only reliable functioning of the artificial leg, but also a great reduction of the risk of breakage; repairs, which are particularly frequent through wear in the case of complicated or particularly sensitive parts of the knee-joint, are here reduced to a minimum and even in the manufacture considerable savings in cost are achieved.

The knee-joint according to the invention is described hereunder in greater detail with reference to one embodiment, which is illustrated in the attached drawings, wherein:

Figure 1 shows the front view of an artificial leg with knee-joint, partly in section,

Figure 2 shows the side view, likewise partly the socket 2 in the upper part of the artificial limb. are mounted resiliently yielding transverse parts 5, preferably of soft rubber, which keep the socket 2 of the knee-joint under more or less heavy pressure. The joint itself, together with the lower limb 6 of the artificial leg fastened thereto rests on. an accordion type of double hinged joint I provided therebelow on the bottom of the cavity 3. The spherical part 8 of the upper limb 4 of the artificial leg runs in the plane of Figure 2 concentrically to the axle I, and is provided with a recess 23 of wedgeshaped cross-section (Figures 1 and 2) into which engages a projection It on the lower limb G of the same wedge-shaped cross section and likewise curved concentrically to the axle I (see particularly Figure 1). On its other face the projection 10 carries a pad H, opposite which lies the face l2 of the recess 9, so that when the knee is stretched contact is made as gently and noiselessly as possible. The rocking movement to the rear is limited by the face l3 of the cavity of the hollow of the knee.

When the knee-joint according to the invention is operating, the sequence is as follows:

When the artificial leg is loaded by the wearer at the beginning of a step, in consequence of the elastic mounting of the socket 2, the upper limb 4 is pressed with its cavity 9 firmly on to the wedge I0 of the lower limb. The upper and lower limbs are now connected to one another rigidly through the mutual engagement of wedge and recess, and hence form a unit without flexibility. The load on the axle l of the knee-joint is at the same time completely cancelled. Towards the end of the step movement the artificial leg is gradually relieved of load, and the weight of the body is transferred more towards the ball of the foot and the toes. With the simultaneous reduction of the pressure of the brake parts 9 and In on one another, the

transmission of the weight is now transferred to the surface I2, so that a movement is produced there which effects the complete release of the brake 9, It; the lower limb can swin freely until, when the artificial leg is brought forward, the stops H and i2 come into engagement once more, whereupon the pad H ensures entle andnoiseless contact.

The more the wearer takes the weight of his body on the artificial leg, and the more calmly and therefore more slowly he loads it, the more reliable will be the firmness of standing and walking. These important factors force the wearer to adopt a normal method of walking with small steps, and thus lead to a considerable saving of energy as compared with the force-consuming crooked gait with wide steps which is so often observed and which arises principally from an instinctive lack of trust in the reliability of known designs of artificial limbs, particularly at the moment of taking the Weight at the beginning of a step and is due to a badly fitted basket for the upper limb stump only in the case of a small perand walking, while when he walks with the leg extended a feeling of insecurity increases to the same extent so that the artificial leg designed in accordance with the present invention forces the wearer, as it were, to adopt from the very beginning the correctand most favourable method of walking. The learning to Walk, which'is otherwise customary and involves a waste of time not only for the wearer but for the maker also, is entirely dispensed with. Since the wedge it of the corresponding cavity 9 can, be accurately adjusted to 1-2 mm. the wearer feels the slight shortening of the artificial leg from the moment of treading on, it until the joint isreached as a natural feeling. The brake lining can be selected according to the eifect desired.

The heavy stretching of the knee axle l and of the supporting bars M which occurred hitherto is now almost completely eliminated, so that the danger of breakage is greatly reduced. Wear on the socket 2 is also substantially reduced, since a rotary movement takes place in thebore thereof when the lower limb swings without load, while the brake wedge iii transmits the full load of the upper limb, together with the weight of the body.

Series production of the new artificial leg is very simple. Factories can be changed over to its manufacture at little expense. The hollowing out of the knee part in the lower limb can be attended to in one operation by a milling cutter, which at the same time cuts out the brake wedge. The exact fitting of the knee stop of metal hitherto'provided is entirely dispensed with, since the brake wedge I0 is designed as a stop on the face side.

The knee-joint of the invention may be built into almost all artificial limbs of introduced designs. The weight of the artificial legs will be rather reduced, but in any case will not be higher than hitherto. The materials which can be used are wood, metal, particularly light metals, and synthetic materials of any suitable type.

-We claim:

1. A knee-joint for artificial legs comprising an upper and a lower leg section, said upper leg section having a downwardly extending spherical projection and said lower leg section a correspondingly shaped recess for coaction'withsaid rojection, said upper leg sectionbeing provided with a cavity, a socket vertically moyably lo cated in said cavity and resiliently supported therein, a transverse pin pivotally connecting said leg sections and carried by said movable socket, said spherical projection being provided with a downwardly expanding wedge-shaped recess, a correspondingly shaped'projection on said lower leg section and extending into said recess, said projection and said recess adapted to form braking faces upon their mutual approachment by a load exerted upon the foot, said braking faces being inclined relative to the direction of the load.

2. A knee-joint according to claim 1, characterized therein, that the socket enclosing cavity and the socket have a rectangular shape.

3. In a knee-joint according to claim 2, springs located between the lower face of said displaceable socket and the walls of the socket housing cavity.

4. In a knee-joint according to claim 2, resilient pads located between the upper face of said displaceable socket and the upper leg section.

JiiRGEN FISCHER. PAUL RICHARD KLUGE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Caron May 30, 1950 

